SCHEDULE 13G

CUSIP No.

946784105

Names of Reporting Persons

Derby LuxCo S.a r.l.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

LUXEMBOURG

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 32,645,525.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 32,645,525.00
8	Shared Dispositive Power 0.00

Aggregate Amount Beneficially Owned by Each Reporting Person

32,645,525.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

18.7 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

CUSIP No.

946784105

Names of Reporting Persons

EQT Fund Management S.a r.l.

Check the appropriate box if a member of a Group (see instructions)

(a)

(b)

Sec Use Only

Citizenship or Place of Organization

LUXEMBOURG

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 32,645,525.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 32,645,525.00
8	Shared Dispositive Power 0.00

Aggregate Amount Beneficially Owned by Each Reporting Person

32,645,525.00

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in row (9)

18.7 %

Type of Reporting Person (See Instructions)

SCHEDULE 13G

Item 1.

(a)

Name of issuer:

Waystar Holding Corp.

(b)

Address of issuer's principal executive offices:

1550 Digital Drive, # 300, Lehi, Utah 84043

Item 2.

(a)

Name of person filing:

This Schedule 13G is being filed jointly by Derby LuxCo S.a r.l. ("Derby") and EQT Fund Management S.a r.l. ("EFMS") (each a "Reporting Person" and, together, the "Reporting Persons"), pursuant to an agreement of joint filing. Several investment vehicles collectively make up the fund known as "EQT VIII." EQT VIII owns 100% of the membership interests in Derby. EFMS has exclusive responsibility for the management and control of the business and affairs of investment vehicles which constitute the majority of the total commitments to EQT VIII. EFMS is overseen by a board of not less than three individuals that acts by majority approval. EFMS may be deemed to beneficially own the shares of Common Stock (as defined below) directly owned by Derby, but neither the filing of this Schedule 13G nor any of its contents shall be deemed to constitute an admission that EFMS is the beneficial owner of the Common Stock referred to herein for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended (the "Act"), or for any other purpose and EFMS expressly disclaims beneficial ownership of such shares. The filing of this statement should not be construed to be an admission that any of the Reporting Persons are members of a "group" for the purposes of Sections 13(d) and 13(g) of the Act.

(b)

Address or principal business office or, if none, residence:

The address of the principal business office of Derby is: 51A, Boulevard Royal L-2449 Luxembourg Citizenship: Luxembourg The address of the principal business office of EFMS is: EQT Fund Management S.a r.l. 51A, Boulevard Royal L-2449 Luxembourg Citizenship: Luxembourg

(c)

Citizenship:

Derby LuxCo S.a r.l. - Luxembourg EQT Fund Management S.a r.l. - Luxembourg

(d)

Title of class of securities:

Common Stock, par value $0.01 per share

(e)

CUSIP No.:

946784105

Item 3.

If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:

(a)

Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);

(b)

Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);

(c)

Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);

(d)

Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);

(e)

An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);

(f)

An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);

(g)

A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);

(h)

A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);

(i)

A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);

(j)

A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:

(k)

Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).

Item 4.

Ownership

(a)

Amount beneficially owned:

The information contained in rows 5, 6, 7, 8, 9, 10, and 11 on each of the cover pages of this Schedule 13G and the information set forth or incorporated in Item 2(a) is incorporated by reference in its entirety into this Item 4. As of June 30, 2025, Derby directly holds 32,645,525 shares of the Issuer's Common stock, par value $0.01 per share ("Common Stock"). EFMS may be deemed to beneficially own the Common Stock directly held by Derby.

(b)

Percent of class:

Each of the Reporting Persons may be deemed to be the beneficial owner of the percentage of Common Stock listed on such Reporting Person's cover page. Calculations of the percentage of Common Stock beneficially owned are based on 174,146,070 shares of Common Stock outstanding as of June 30, 2025, as disclosed in the Issuer's Quarterly Report on Form 10-Q filed with the U.S. Securities and Exchange Commission on July 30, 2025.

(c)

Number of shares as to which the person has:

(i) Sole power to vote or to direct the vote:

See each cover page hereof.

(ii) Shared power to vote or to direct the vote:

See each cover page hereof.

(iii) Sole power to dispose or to direct the disposition of:

See each cover page hereof.

(iv) Shared power to dispose or to direct the disposition of:

See each cover page hereof.

Item 5.

Ownership of 5 Percent or Less of a Class.

Item 6.

Ownership of more than 5 Percent on Behalf of Another Person.

If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.

The several investment vehicles that collectively constitute EQT VIII may be deemed to have the indirect right to receive or the indirect power to direct the receipt of dividends from, or the proceeds from the sale of, the Common Stock held by Derby by virtue of their ownership of Derby's membership interests. Of these vehicles, EQT VIII SCSp may be deemed to have the indirect right to receive or the indirect power to direct the receipt of dividends from, or the proceeds from the sale of, 5.0% or more of the Issuer's outstanding Common Stock.

Item 7.

Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.

Not Applicable

Item 8.

Identification and Classification of Members of the Group.

Not Applicable

Item 9.

Notice of Dissolution of Group.

Not Applicable

Item 10.

Certifications:

Not Applicable

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Derby LuxCo S.a r.l.

Signature:	/s/ Tinatin Gogoladze
Name/Title:	Tinatin Gogoladze, Manager
Date:	08/08/2025

Signature:	/s/ Sanjay Fullee
Name/Title:	Name: Sanjay Fullee, Manager
Date:	08/08/2025

EQT Fund Management S.a r.l.

Signature:	/s/ Sara Huda
Name/Title:	Sara Huda, Manager
Date:	08/08/2025

Signature:	/s/ Luca Luigi Baggio
Name/Title:	Luca Luigi Baggio, Authorized Signatory
Date:	08/08/2025